Automatic tuning device for radio receivers



July 16, 1940.

A. w. PLENSLER AUTUATIC TUNING DEVICE FOR RADIO RBCEIVERS Filed Nov. 17, 1931 4 Sheets-Sheet 1 July 16, 1940 A. w. PLENSLER 2,208,549 I AUTOMATIC TUNING DEVICE FOR RADIO RECEIVERS Filed Nov. 17, 195'. 4 Sheets-Shea?I 2 July 16, 1940. A w. PLENsLER AUTOIATIG TUNING DEVICE FOR RADIO REGEIYERS Filed Nov. 17, 193'. l 4 Sheets-Sheet 5 July 16, 1940. A. w. PLENsLl-:R

VAUIOIA'IIC: TUNING DEVICE FOR RADIO RECEIV'ERS 4 Sheets-Sheet 4 'fili m. bmx Nu ,J u m N h N @Q NT@ @u w.. ,sal MENU. H ----Jill iyww un mi I` l :SRE 11%) Q SEEC \w\ @s p MN mi um x HHHHINUQ 5% mw. EN p NM PatentedY July 16, 1940 j UNITED STATES PATENT oFFlc-E AUTOMATIC TUNING DEVICE FOR RADIO RECEIVERS Alexander W. Plensler, Chicago, Ill., assignor to Belmont Radio Corporation, a corporation of Illinois My invention relates in general to a device for electrically operating control and-indicating apparatus, and more in particular to an automatic tuning device for a radio receiver, and in this respect is directed to an improvement over the invention of my copending application Serial No. 390,064, filed September 3, 1929, now issued as Patent No. 2,114,068.

It is an object of the present invention to provide an improved electrically operated automatic control device for controllable apparatus such as a radio receiver.

A still further object of my invention is to provide a very compact device capable of tuning the radio receiver to a relatively large number of predetermined stations, yet one which may be mounted in the radio receiver cabinet itself immediately adjacent the tuning and control apparatus therefor, so as to provide as direct mechanical and electrical connections with such apparatus as possible.

One of the features of my automatic tuning device is the provision of a staggered assembly for the electrical selector contact elements so that there will be a minimum of lost space in the device and consequently make it as compact as possible.

A further feature of my present invention is the provision of rotary electrical contact elements which may be preassembled as a unit and relatively stationary electrical contacts therefor which may also be preassembled as a unit, the two units being of such construction as to be readily assembled together, the preassembly of each unit simplifying the testing and inspection thereof and facilitating the completel assembly of the device. Another feature is the provision of two electro-magnetic clutches for connecting different receiver control elements to the driving motor for the complete apparatus, which clutches are positive in this operation yet provide for a simple disengagement of the motor even when operating, in the event the apparatus is not stopped at the end of the normal operating arc for the tuning condenser.

The present invention also provides for remote control not only for broadcast stationv tuning, but also for the speaker volume, and accomplishes bothoperations by motor drive. Y

A still further feature of my invention is the provision of control apparatus and acircuit for quickly moving the condenser through all or part of the complete arc through which it normally travels.

Other objects, features, and advantages will be apparent from the following description with the drawings, in which:

Fig. 1 is a side elevation of the complete assembly of the tuning condenser, and automatic tuning device and driving mechanism-therefor for mounting on a radio receiver chassis.

Fig. 2 is an explosion view of one cam unit.

Fig. 3 is a fragmentary sectional view of two cam units on their mounting shaft.

Fig. 4 is a sectional view along the line 4 4 of Fig. l showing particularly the internal structure of the tuning unit as weil as the clutch assemblies' for connecting and disconnecting the driving motor from the automatic tuning structure.

Fig. 5 is a fragmentary view, partly in section, along the line 5-5 of Fig. 4 and looking in the direction of the arrows indicated thereon.

Fig. 6 is a detailed view of a stationary brush for a cam unit in its non-expanded position before mounting on the cam assembly.

Fig. 7 is an enlarged fragmentary sectional view of the adjusting means for an armature on a movable selector finger.

Fig. 8 is an enlarged detail view partly in section of the clutch shifting mechanism for the electro-magnet.

Fig. 9 is an enlarged fragmentary view, partly in section, of the movable armature for the clutch magnet.

Fig. 10 is a diagrammatic illustration of the circuit and part of the control structure for an A. C. circuit for the complete tuning device.

Fig. 1l is a diagrammatic illustration of the comparable circuit for the tuner operated by a D. C. motor.

In the illustration of Fig. l, the ordinary variable condenser ll for a radio receiver is connected through suitable reduction gears G on its shaft Il to a tuning knob l2 carried on a shaft I3 for manual movement and positioning of the tuning condenser l0 as shown by the indicator on the dial I4 visible at the front of the radio receiver cabinet. The speaker sound output for the receiver is controlled by the knob I6 on a shaft l'l extending from the front of the cabinet through an on and. 01T switch i8 (Fig. l) for the radio receiver, to the automatic tuning device as will be hereinafter described. A motor i9 mounted beneath the control elements of the tuning device will selectively drive shaft i3, or shaft l'l, through magnetic clutches in connection therewith.

To control the operation of the motor, whether it be an A. C. motor or a D. C. motor, which in taken tur-n drives the tuning mechanism forA the receiver in response to such control, a plurality of cam units are assembled on a shaft 2| integral with, or coupled to the shaft of the condenser. The cam units are retained in set position on the shaft by means of frictional engagement between adjacent cam units with the frictlonal pressure being varied by the axial position of a nut 22 threaded onto one end of the shaft 2| to press the cam units against a bushing and shaft coupling assembly 23 at the opposite end of the shaft. A pinion 20 is secured to a stub shaft journalled in the frame wall and having a screw driver slot D in the outer or right hand end as viewed in- Fig. 1, for insertion of a screw driver to rotate the shaft and pinion, to in turn rotate the gear 20' secured to the nut 22 to cause axial movement of the nut on the threads of the shaft and thereby vary the frictional pressure on the cams. This frictional pressure is such that it will retain the cams in van angular position on shaft corresponding to the desired station setting. yet such that it will permit the manual rotation of the shaft while retaining a cam stationary so as to change the angular position. It is understood that there will be no necessity to operate the friction varying means .unless the friction de- Y creases through wear, or is too great to permit resetting.' Resetting of a cam unit is ordinarily accomplished with normal frictional pressure on the cam units. It is further .understood however that the simple mechanism for accomplish' ing variation of the frictional pressure permits of a complete clamping of the cam units on the shaft, so that resetting may be effected only after the pressure has been reduced by the simple means described above. The cam units may then beV tightened up again. Each cam unit is identical and any desired number may be assem bled on the shaft 2| depending upon the des'ires of the manufacturer. In the embodiment illustrated herein, a total of ten (10) cam units are shown, making it possible to set the tuning device for the radio receiver to ten (10) ypredetermined broadcast stations. Two complete units are shown in Fig. 3, While a single cam unit is illustrated in detail in Fig'. 2. This general structure is described and illustrated in my copending application noted above.

For convenience I will merely describe one unit, in this improved structure, and it is understood l that the other units are identical. A unit normally comprises a pair of identical cam segments or sections 24and 26 mounted on the shaft 2| and insulated therefrom by means of fibre positioning washers 21. These washers t rather snugly on the shaft 2| and are positioned in cavities 28 formed in the one-piece stamped out cam segments 24 and 26. Each cam segment comprises an embossed ring 29 forming the wall of the cavity 28, and an integral plate portion 3| is provided with alternate apertures 32 and projections 33. A fibre `spacer disc 34 with apertures 36 therein corresponding to the projections on the' two cam segments insulates one segment -from the other over .the complete body portions apertures 32 in the segments are quite a bit larger in diameter than are the projections 33,

aaoacio so that when the latter extend through the disc 34 they will still be spaced away from the metal of the oppositely disposed cam segment, and thus be insulated therefrom. An inwardly turned flange 31 on each of the cam segments extends over slightly less than one-half (1/2) of the periphery oi each segment so that when the segments are brought-together on the shaft 2|, the iianges extend in opposite directions and yet are spaced from one another by contact and mechanical locking gaps 38 formed on each side by virtue of the length of the two anges 31. With each flange 31 extending almost 180 over the periphery of the cam segment, this corresponds with the 180 arc through which the rotors of the tuning condenser ill rotate. In this manner ange 31 of segment 24 for instance, may travel in a clockwise direction through all or a part of the condenser arc of depending upon the particular cam setting while the flange 31 of the segment 26 may similarly travel through the same arc in a counter-clockwise direction.

With the cam units mounted on the shaft 2| as shown in Fig. 4, they are spaced apart from one another by means of steel locking washers 39 having a key` or lug 4| thereon for engagement with the key'way d2 on the shaft 2| to spline each washer on the shaft and prevent its rotation thereon. The steel washers are slightly smaller than the fibre discs 21 so that there is no possibility of engagement with the embossed ring 29 on` each cam segment to make' electrical connection with the shaft 2 I. Each cam unit excepting the washers 39 may be rotated on the shaft 2| for setting to a predetermined tuning position as will be hereinafter explained, and with the Washers 39 desirably stamped from spring stock and bowed slightly, the frictional engagement between the fibre washer 21 and its viously been described. If the dimensions of the shaft and cam assembly are such' that the units described will not occupy the desired axial space, one or more ordinary metal washers may be inserted over the shaft to lie between adjacent keyed washers 39.

The members of a cam unit as illustrated in Fig. 2x may be quickly slipped over the shaft 2| and the cam segments then brought together in proper alignment bymeans of the corresponding apertures 32 and projections 33. These portions as well as the apertures 36 in the disc 34 are of such dimensions that a tight t to maintain the members of the cam unit in a rigid position results from the assembly.l v Y The cam shaft 2| is suitably journalled in plates 46 and 41 of amounting frame for the automatic tuning device, which frameincludestop and bottom plates 48 vand 49, respectively. The cam units on the shaft 2| may be preassembled on plate 41. A second sub-assembly comprising primarily the electrical structure for the cam units,`may be preassembled on the other frame plate 46 and insulated therefrom as well as from the plate 41. as shown in Fig. 4 comprises electro-magnets 5| with the frame therefor comprising a onepiece channelled bracket 52 extending between the frame plates and supported therefrom, and electrically common to all of the laminated cores Sii This latter subassembly 53 having a rear portion 54'extendi`ng through u a corresponding aperture in the base of the channelled frame to'be peened overas at 55, to rigidly retain the laminations in the frame without other securing means. It is understood that there are two such one-piece channelled brackets 52 in the tuning device. An insulated wire winding 56 is provided for each core. Integral fianges-51 extending upwardly and 58 extending downwardlyare provided on the member 52 serving with the core 53 as pole pieces for each magnet. A terminal strip 59 is mounted on the fiange 51, and a strip 59' is mounted at the rear of the flange 8. Connections to the wind-- ings for the electro-magnets 5| extend from the current supply cables C, to the terminal lugs 60 on the strip 59.

The circuit for energizing the split-phase reversible motor I9 to effect operation of the tuner and thereby automatically tune `the radio receiver, extends through a selector finger S to a corresponding single cam unit as shown in Fig. 2. There, of course, is a selector finger for each cam unit and half of the fingers are mounted on one side of the `cam-finger assembly, while the other half are staggered with respect thereto on the other side of the assembly as shown in Fig. 5.

The electro-magnets 5|, with one for each selector finger, are similarly positioned, and with this construction it is possible to mount the cam units closer together. The over-all length of the tuner device is substantially reduced over the structure shown in my copending application identified above.

Each selector finger S on each side of the tuner is mounted upon a downwardly extending resilient finger 6| in a one-piece comb having an integraloonnecting bar 62 (Fig. 1) rigidly secured between a pair of mounting brackets 63 and 63 (Fig. 4) for securing the comb to the tuner frame itself. The lower end of the finger S is formed to provide a vprojection 64 with tapering sidewalls 65 adapted to seat rmly with a wedge-like action in the gap 38 formed at the endsof adjacent fianges 31 on the cam segments 24 and 26. With this configuration when the selector finger is drawn into the gap 38 by the electromagnet 5|., a positive and immediate electrical contact is completed with the two segments 24 and 26, originally insulated from one another, to cause the motor |9 to become disconnected from the shaft 2|. Likewise, the configuration of the 'projection 64 provides for a mechanical stopping of the rotationof the cam unit at the exact predetermined tuned position of the tuning device.

The selector finger S is attracted to the core 53 and faces of the flanges 51 and 58, by anarmature 61 adjustably secured on one side of the finger S by securing means which also secure the selector finger S to the spring finger 6| on the comb. It is desirable that the armature 61 make a full-face contact at all such three points on the magnet to prevent magnetic losses and permit the operation of the magnet on the smallest possible amount of power. It is desirable to maintain the maximum operating efficiency for the magnet and finger structure so that a firm and positive electrical and mechanical engagement of the projection 64 in the cam gap 38 is obtained. A pivotal action on the finger S is obtained by virtue of its mounting on the spring finger 6|, with the latter normallyl holding the finger S out of engagement with a cam unit. To assure the proper alignment bemounting means are provided which comprise two adjusting screws 68 threadably secured in corresponding bushing and mounting members 69 engaging the spring finger 6| and extending through this finger and the selector finger S, as shown in Fig. 7 to hold the two together. Each screw 68 extends in a threaded aperture 1|) in the armature 61. The portion of the screw 68 in the bushing 69 is provided with threads pitched in one direction while the portion in thc aperture 10 has threads pitched in the other direction, and, of course, the threads in the bushing and armature are either left hand or right hand to correspond therewith. With the screw turned in one direction, for instance, one end of the armature will be moved away from the face of the selector finger S while turning the screw in the opposite direction will draw the armature toward the selector finger and thus properly align the armature 61 to provide a full-faced contact on the electro-magnet 5| when the magnet is energized.

Each magnet and selector finger unit is provided with a contact pin 'i3 carried on the terminal strip 59' secured to the flange 58 on the magnet frame. The pin 'i3 is connected to the winding 56 on its corresponding magnet 5| as shown in the circuit diagram of Fig.A 13 and is positioned to extend through a corresponding enlarged aperture 12 (Fig. 4) in the finger S, and is of a length to engage aholding Contact 16 integral with the spring finger 1.6i on the selector comb. The pin 13 engages the contact 16 when the selector finger is draw'n 'in to engage the rim or flange ,31 of a cam segment, and is included in a holding circuit for that finger as will be described. A rubber covered bumper rod 11 extends between the frame plates 46 and 41 on each side thereof, to limit the outward movement of the selector finger as is shown on the left hand side of Fig. 4, for instance.

All of the cam segments to control clockwise movement of the motor are connected electrically in parallel, and similarly with all segments -for counter-clockwise movement, as can be seen from the circuit diagram of Fig. 13. To conserve parts and space and simplify the assembly of the tuning device the cam units are assembled back to back, so to speak. Adjacent cam segments have the same angular displacement, while the flange 31 on each of the other segments`of two camunits are angularly displaced 180 with respect to those first mentioned. 'I'his is shown in Fig. 3. As a result, a single stationary brush 18 may be Aused to engage two adjacent cam segments because they are both connected to provide the same direction of rotation for the motor. As shown in Fig. 6 each brush 18 has a pair of resilient fingers 19 and V8| extending from one side of the .U-shaped body portion which is soldered or otherwise permanently secured inv electrical and` physical engagement with a metal rod 82 mounted between the two frame plates 46 and 41 and insulated therefrom. The ends of the fingers 19 and 8| are turned outwardly to permit the brush as a whole to be slid over the rim. 29 of the embossed portion of each cam segment. The spring pressure on the fingers causes them to remain in positive electrical contact with each corresponding segment and providing two fingers instead of .one gives greater assurance of continued 'electrical contact. These cam brushes 18 are staggered as described for the selector finger land electro-magnet units, and as shown in Fig. 5 a total of eleven (11) brushes are required for the ten (10) cam units.

-All the parts of the selector nger and magnet assemblies as well as all of the parts of each cam unit, including the stationary brushes, are of such a. conguration that the same part can be used either on the left or on the right hand side of any of the assemblies. This, of course, reduces the cost of manufacture materially and facilitates the assembly of the complete device.

The motor is thrown in and out of connection with the tuning shaft I3 and volume control shaft I1, having the receiver switch I8 thereon, by means of electro-magnetic clutch structures C and C' respectively. The clutches are identical as employed in the illustrated embodiment of my invention so far as the principal part of their assembly is concerned, and for convenience, simply the clutch C for the tuning shaft I3 will be described. As is shown in Fig. 1, the shaft I3 or a coupled continuation thereof, extends entirely through the clutch frame F and has a gear collar 8d slidably 'secured thereon, with suitable gearing 85 thereon for connection to the motor gears. The collar 84 also carries an apertured disc 86 rigidly secured thereto, and axially aligned with a corresponding disc 81V integral with or secured to a sliding collar 88 on the shaft I3. Pins 69 on the disc 81 extend through corresponding'apertures in the disc 86 to ride therein and cause disc 86 to drive disc 81 and consequently the collar 88 having the clutchplate 9| on the oppo- -site end thereof. The clutch plate9| is provided with spaced apart pointed prongs 92 (Fig. 1) for engaging the serrated rim 93 of the driven clutch plate 94 integral, or rigid with the'sleeve 96 secured to the shaft I3.

When the clutch electro-magnet 91 is nerg-ized the armature 98 on the shifting lever 99 is attracted to the face of the laminations or core |0| of the magnet to shift the clutch plate 9| into engagement with the corresponding clutch plate 94 having the serrated rim 93 thereon (Fig. 8). This, of course, causes the motor I9 to drive the tuning shaft I3. 'I'he clutch plates are normally out of engagement as a result of the tension of the spring |00 pulling the lever 99 away from the magnet when it is deenergized.

The shifting lever 99 comprises a. stamped out bar |02 pivoted on the clutch frame at |03 and extending upwardly to a U-shaped portion |04 straddling the collar 88 'and being confined thereon axially by the discs 81 and 9|. n clutch C, as shown in Fig. 4, an extension |06, integral with one leg of the U-shaped portion, is provided with a hooked top for engagement with the buttonv |01 on the muting switch |08 shown more clearly in the diagrammatic illustration of Fig. 10. A lip |09 on the body portion of the lever |02 extends forwardly to engage the back of the disc 9| to prevent the lever member fromfioating or rattling on the collar 88. A

The armature 98 is carried in a oating connection with a cross bar integral with or secured to the 'lever |02, and is positioned and supported 'by pins ||2 (Fig. 9) from the armature extending through apertures in said cross bar, and normally retained against the cross bar by the tension on the spring ||3 carried on the threaded pin ||4. This floating connection acts, in effect, as a safety valve when the sweep switch is being operated, as will be explained, so that in the event the` motor is maintained energized to ordinarily rotate the rotors for the condenser |0 beyond their limit of rotation, at such limits, due to the stopping of such rotors in the normal manner, the rounded ends of the prongs 92 ride over'the rounded surface of the serrations ing force exerted onit at its limit of movement if the clutch remained in engagement.

As mentioned above, the clutch structures C and C', including the electro-magnets therefor, are identical in their principal mechanical parts. However, as is yshown in the circuit diagram of Fig. 10, the electro-magnet 91 of 'clutch C has a pair of windings |20 and -|2I thereon, while the clutch structure C' with core |0|"hasonly a single winding |22 thereon. The differences in the operation of these two magnets will be explained in detail hereinafter. Shading rings |23 are provided onthe laminations of each of the electrofmagnets to increase and smooth out the coercive force exerted by the magnet on the armature when excited by A. C. to prevent chattering of the armatures 98 and 98' thereon, as will beexplained in connection with the circuit diagram of Fig. 10. When using an A. C. motor, the D. C. supply to the tuner is used only for operating the electro-magnets 5|. `When using a D. C. supply to the electro-magnets for the clutches,

this, of course, eliminates the necessity for the' shadingv rings.

' A. C. motor circuit and operation As to the operation ofthe tuning device with an A. C. motor and a circuit in accordance with the diagram of Fig. l0, the device is set into operation by pushing one of the buttons as I at the receiver or a button as I' at the remote control unit R.

As is shown in the diagram, each of these buttons -such magnet to attract the armature 61 which in turn pulls the selector nger S, secured to the armature 61, against a segment such as 26 on the tuner cam. It is understood that the tuner will be driven clockwise for one segment of the cam, and counter-clockwise when the iinger engages the rim 31 on the other segment of the cam. One segment is connected with one side of the split phase motor I9, through clutch winding |20 while the other segment is connected to the other side of the split phase motor I9 through the clutch winding |2I. pleted substantially instantaneously with the pressing of the button I, which under pressure of the spring tension in the strip |28 then returns to normal position and the circuit through-the driving motor is maintained by a holding circuit as will be explained. With the selector iinger in engagement with segment 26, the current passes through one of the metal bars 82 carrying a stationary brush 18, to winding |20 on the clutch magnet 91 of clutch C. Winding |20 is in. series connection with iield winding |31 of the A. C.

The above circuit is comj more particularly to the contact member 16.

As current passes through the magnet winding l20, the magnet is energized yto attract armature 98 which causes the shifting lever |02 to move,

and the arm |06 thereon to engage the button |01, and open the contacts |48 and |49 of the switch 08. This opens the speaker circuit including the output transformer secondary |85, and the voice coil |86, so that the noise of tuning will not be reproduced therein. This action simultaneously closes the contacts and |52 on the other side of the switch |08. This closes a holding circuit for the selector nger S whichextends through lead |53 and |41 to the holding contact 16 on thevselector nger S, from which contact 16 the current extends through the pin 13 to the winding 56. On the other side of the switch |08 the circuit extends through the contact |52 of the switch and over the lead |54 tothe negative side of the D. C. supply. With the closing of this circuit, the motor remains energized and the selector nger S remains in engagement with the segment 26 by virtue of the attractionof the armature 61 to thevmagnet 5|.

With the motor energized and connected through the clutch to the tuning shaft 2|, common to both the rotor-and the tuning condenser, this shaft turns until the projection 64 on the nger S engages both segments 26 and 24 at the gap 38. This gap represents the predetermined station setting for the tuning condenser. With such simultaneous engagement, a circuit is completed through segment 24,'through the stationary brush 18 in engagement with that segment, through the corresponding bar 82 as shown in the lower position in Fig. 10, and then to winding |2| on the magnet 91. In the meantime the circuit through segment 26 and the other bar 82 and con-l necting wires to Winding |20 is maintained. The current phase in these two circuits is opposite and causes the eld of the windings |20 and |2-| to collapse, thereby deenergizing the magnet 91 to in turn release the armature 98. As the armature 98 is released, it acts to simultaneously disengage the discs 9| and 93' to break the mechanical connection between the motor and tuning shaft. As

a result, the driving mechanism is entirely re-A I leased from the driven shaftv |3 before the elec-V trical circuit holding the projection 64 in the gap 38 is broken and, as a result, there -is positive stopping of the, cam at the predetermined station setting represented by the gap 38. The cam stops immediately under such mechanical braking although the armature of ythe motor I9 maycoast under its own momentum. Upon release of the armature 98, the contacts |5| and |52 in switch |08 are opened to break the ,holding circuit. When the circuit at contacts |5| and |52 is broken, the circuit including D. C. supply |35 is also broken to cut oi the D. C. supply to the winding 56, to deenergize the magnet and release the retaining finger 16, thereby releasing the selector nger S from the gap 38.

All-4 of the selector circuits including buttons I, II, etc., paralleled of course by the corresponding buttons I', II', etc., in the remote unit R, and each in series with its respective holding magnet 5|, are in parallel, so that the same operation results from pushing in any one of the buttons as is described in connection with the button I above. In this connection it is noted that allrof the. various manually operated switch circuits are in parallel connection, so that no harm will come to the mechanism even though more than one switch is manuallyoperated at the same time. When the first selector contact shorts the two segments of one of the energized cams under these conditions, all of the holding circuits will be opened.

The remote control device, shown diagrammatically in Fig. 10, contains a toggle switch |56,

which, when operated in either one direction orl the other as a single-pole double-throw switch, closes a circuit throughthe winding |22 of the electro-magnet for the clutch C' atthe receiver. This energizes the magnet core |0 to attract the armature 9B' which in turn actuates the clutch C' (Fig. 4) to connect the motor I9 to the shaft l1 for conventional volume control in the radio receiver. The volume control is rotated one way or the other depending upon which direction the switch handle is moved so as to provide complete control of the volume of reproduction of the radio receiver from a remote position. The on and olf switch I8 for the receiver is mounted on the volume control shaft |1 and operated in the usual manner, so that the receiver may also be turned on and offfrom the remote position. Either of these operations is accomplished without movement of the tuning cams, or rotors. It will be noted that the circuit through the single winding |22 for the magnet core |0| extends from switch |56 directly through such winding and one or the other of the windings |31 and |31 of the motor itself. This circuit more in detail includes the conductor extending from the single contact on the switch |56 through the winding |22 to the conductor |53, the conductor |46, contacts |43 and |44 which are normally closed, and conductor |4| to the energizing source at |39'. Assuming that the movable contact on the switch |56 is moved'upwardly, thelremainder of the circuit extends fromv the energizing source |39 through the winding |38, winding |31', and the conductor extending therefrom to the power contact in the switch |56. This circuit does not extend through the tuning control clutch magnet 91 with windings |20 and |2|, so that with this direct connection to the motor, such motor may be used for anyone of three different operations, viz., for operating the tuning shaft, for operating the shaft |1 to operate the switch |8 for on and off switching, or for operating the shaft |1 to in turn operate a volume control device for the radio receiver. This circuit for both tuning and switching permits the use of one, or a plurality of remote positions.

A particular cam is angularly adjusted on the shaft 2| so that the angular position of a gap l 38 corresponds to a predetermined broadcast station setting of the condenser I0 by means vincluding the reset switch |42. The setting or resetting operation includes the original energization of the tuning circuit described above, by pushing a button as I, to cause the cam to turn until the projection 64 engages the gap 38. It is understood, of course, that each cam or rotor unit, frictionally mounted upon the control shaft, may be operated independently of the others, and similarly, each rotor unit may be reset independently of the others, so that the button depressed is that for the particular cam whose station setting it is desired to change. After the button I has been depressed to make contact, it"v is released in the usual manner. After the .rotor has rotated in the manner described above until the projection 64 engages the gap 38, the motorcircuit is broken by the collapse of the' magnetic eld at the magnet 91 and the finger S returns to the normal non-operating position as shown on the left-hand side of the structure in Fig. 4 with the projection 64 opposite the gap 38. Button I is then depressed again to throw projection 64 into gap 38, and in this instance, of course,

the clutch will not operate.l While -button I is maintained depressed the button on the reset switch |42 is depressed. While holding the latter button depressed the button Iy is released. Acircuit is then completed through contacts |51 and |58 to one side of the D. C. supply |85 through leads |59 and I6|. The other side of the circuit extends through leads |46 and |41, nger con tact 16, pin 13, winding 56, and lead' |36 to en ergize the magnet and maintain the projection 64 in the gap 38 without at the same time energizing the motor windings inasmuch as that circuit is broken at contacts |43 and |49. With the cam. retained mechanicallyagainst rotation, the knob I2 on end of the tuning shaft I3 is turned to move the condenser to any desired' tuning position as shown on the dial I 4. When the condenser 0 is properly positioned for the der'.

sired station the shaft 2| will, of course, have attained an angular position with respect to the cam,'such that stopping the cam at that point subsequently will tune the radio receiver to that predetermined station. i,

If the operator of the radio receiver is manually tuning the same, and wants to tune a station substantially at the'opposite end of the wave l t band to that to which the receiver is tuned when the operation is begun, the condenser may be moved through its 180 of rotation, or any lesser amount, more quickly than can be accomplished by manually tuning itself, by operating the sweep switch` |63 available at the front of the radio reeciver. This switch operates to close the motor circuit and the circuit through the clutch and attracting the armature 98 thereto to shift the movable clutch plate 9|. The circuit continues through the motor winding |31, winding |38, A. C. supply |39, lead |4|, through contacts |43 and |44,`1ead |46, and lead |66 back to the switch. The rotation of the condenser can be stopped at any desired position by merely moving the sweep switch to a center position as shown in Fig. 10. The receiver may then be tuned manually if desired to obtain a fine adjustment, or, of course, the tuning device may A be operated to get the peak tuning for the station desired if a cam has been previously set for the station desired. This eliminates the necessity of tuning the manual knob l2 with a high gear ratio from one point of the dial to the other point of the dial, if manual tuning at that particular time is desired. the speaker is muted during this operation.

It is noted, also, that With reference to -the remote control' operation, it is, of course, understood that the switch |56 causes energization of the clutch C', and the motor I9 to rotate the shaft |1 having the switch I8 thereon. However, inasmuch as the motor cannot again be energized from the A. Crysupply |39 to drive the shaft I1 when the switch |8 has been turned oil' from the remote position, a separate source of A. C. is provided for the motor for energization from a remote position when the switch I6 is oi.

D. C. motmcircuit and operation To operate the tuner with a D. C. motor (Fig. 11), a button I in Fig.l 1l is depressed exactly as described in connection with the A. C. motor circuit. Upon depressing the button, the circuit extends from the D. C. vsupply |35 through lead `|36 to the winding 560i the magnetl 5|, energizand contact i'lnger 16 is completed through' the finger S engaging one of the cam segments as 28, lead-82, magnet winding |20, lead |1|, motor windings |31" and |38', lead Ill to reset switch |42'. From switch |42', and particularly contacts |43 and IM' the circuit continues through lead |12 to the positive side of the current supplyT at |35. Tracing the circuit backwardly from the 'nger contact 16, the circuit extends through lead |41', |53', contacts I5| 'and |52 which have been closed by the movement of the armature to the magnet core I 0|, as heretofore The motor operates when originally energized' byv engagement of nger S with a cam segment, and acts to drive the cams in the same manner as described with respect to the A. C. motor.

Similarly, the clutch magnet is deenergized, and' the motor circuit then broken when the projection 66 contacts the two segments at the gap 38 as heretofore described. x

To originally set or to reset a cam for the desired broadcast station tuning, the cam to be changed in angular position is rotated by the energizing of the motor circuit YIas described above. The button, as I, is again depressed to attract the armature 61 vto the magnet 5| and pull the. projection 64 into engagement with the cam segments at the gap 38 in thesame manner as described with respect tothe A. C. circuit. While holding the button I depressed as previously described, the button on the reset switch |42' isl pressed down to open the contacts |43 and |44 and close the contacts |51 and |58'. f This closes a circuit extending from the D. C. supply |35 through lead |36 to winding 56, through pin contact 13, nger contact 16, lead |41', lead |46' through the contacts |51 and |58' and lead |59' back to the negative side of the D. C. supply through lead |6I. l

'I'he sweep switch |63 for the D. C. circuit. is identical with the switch designated by the same reference character for the A. C. circuit. Similarly,the operation is the same, viz., the switch is moved up or down as viewed in Fig. 11, to energize either the counter-clockwise or clockwise Winding for the D. C. motor I9'. To describe this circuit fer movement of the tuning cams in one direction, the switch may be considered as pulled downwardly as viewed in Fig. 11. then extends through the winding |28 of the clutch magnet 91 to draw the armature B8 thereto and thereby move the clutch'into engagement. The circuit also extends through the winding |31" of the motor, |38', lead |41', and the contacts l|43 and |44 of the reset switch |42. The lead |12 from these contacts is connected to the D. C. circuitsupply at |35. The other side of the circuit extends from the center contact of the "sweep switch |63 through lead |65 to a connection with lead |69 which in turn is connected to the other side of the D. C. supply at |35.

The remote control switch |56 for the D. C. motor operates to energize the motor and clutch C with its connected electro-magnet so that the radio receiver may be turned ofi or on from the remote position, and similarly so that the volume control may be actuated from a remote position. The clutch C', of course, connects the motor only with the shaft' |1 carrying the on and off switch and volume control thereon. When pressing the switch downwardly as viewed in Fig. 1l, the circuit is completed from the direct current supply at |35 throughthe lead |12 and through the contacts |43' and |44' of the reset switch.

'I'he circuit then extends through lead Ml' to the motor winding |38' and then through the winding |31" and lead |16 to the switch |56. The center contact of the switch |56 is connected into the other side of the circuit extending through the lead |11, the Winding |22 of the electro-magnet for the clutch C' through lead |18 to lead |54' which connects with the lead IBI extending to the minus side of the D. C. supply at |35. Upon energization of the electro-magnet for the clutch C', thel armature 98 is attracted thereto and the clutch members brought into engagement for connecting the motor and the drive l shaft |1 as heretofore explained.

When the tuning'device of my invention is operated either by an A. C. or a D. C. motor, and consequentlyu operating on an A. C. or a D. C. circuit, if one button is pressed in and a cam unit set into motion, pressing of another button merely causes the selector finger corresponding to that button to .engage the rim of a segment of its corresponding cam. The tuner will then stop at the predetermined station setting corresponding tothe gap 38 which is reached first by a selector iinger for the first operated button or the second operated button. In other words, pressing more than one button will cause no injury 'whatever to the mechanism, but will merely cause the deenergization of the electro-magnet for the clutch C when the rst short circuit across two corresponding cam segments is accomplished. Of course, if the operator actually desired to tune the station whose button was i'lrst depressed.

while the gap 38 corresponding toa subsequently depressed button is reached iirst in the rotation of the shaft 2|, the operator will have to depress the iirst button a second time. However, there should be no occasion to press more than one button at a time unless 'the operator' is merely experimenting with the tuning device so that no inconvenience will be caused. On the other hand, by operating the tuner in the manner described above, the device becomes substantially fool proof-against injury due to such experimentation because regardless of the number ofbut- The circuit tons depressed, no harm can befall the mechanism.

From the foregoing description and a consideration of the drawings therefor, it is apparent that I provide a compact, sturdy, and relatively simple electrical automatic tuning device for radio receivers. The commercial embodiment of the invention tunes to a substantially hair-line predetermined station setting and by virtue of the structure for retaining the cams on the shaft 2|, and by virtue of the selector finger and electromagnet structure, this same station can be tuned in time after time with the same accuracy. Resetting of the relative position between the shaft 2| and consequently the variable condenser I0, and the individual cam units, is accomplished quickly and simply so that the tuning device has substantially unlimited flexibility so far as automatically tuning any desired station over a broadcast band.. No `supplementaltools or devices are required to accomplish this setting asis necessary in many of the prior art .devices so that the operator of the radio receiver can likewise completely operate the tuning device by merely utilizing the mechanical and electrical structure all permanently mounted on the radio receiver cabinet or at the remote control unit.

Although this improved electrical automatic tuning structure has been illustrated and described in its preferred embodiments. it is understood that my invention is not limited thereby, but rather is limited only by the scope of the appended claims. f

1. In a control device for controllable apparatus, power means for actuating said device, and means for controlling the actuating interval for said power means including a pair of adjacent rotary units, and means for extending a circuit through one unit or the other comprising a movable contactwith magnet means for each rotary unitvfor selectively attracting a contact into engagement with its corresponding unit, and a fixed brush common to both units and in continuous engagement therewith comprising'a pair of spring ngers adapted to be spring pressed against two radially spaced portions on each of said control units.

2. In a control device for controllable apparatus, power means for actuating said device, and means for controlling the actuating period for said power means including a` plurality of coaxially assembled rotary contr/ol units, each of said control units comprising a pair of insulatingly separated conducting segments with one segment adapted to control the clockwise rotation of the unit and the other the counterclockwise rotation thereof, with said control unit-s positioned with respect to one another in the coaxial assembly in a manner such that each two adjacent conducting segments of adjacent control units are both adapted for either clockwise or counterclockwise rotation control, means for extending control circuits through said control units including a movable contact for each control unit, and a fixed contact common to each two adjacent conducting segments for adjacent control units.

3. In a control device for controllable apparatus, a rotary shaft, a control unit on said shaft comprising a pair of conducting members, an insulating disc intermediate said members, insulating means on the'outside of each member and supporting said members out of contact with the shaft, and a washer keyed to said shaft and positioned adjacent an -insulating means at the outside thereof. A

4. Ina control vdevice for controllable apparatus, a rotary shaft, a control unit on said shaft including a pair of complementary conducting discs, an insulating plate intermediatesaid discs to insulate one from the other, and means for maintaining said discs in relatively fixed relation including laterally extending projections on each' disc fitting snugly vin correspondingl apertures in said insulating plate to fix each disc with respect to said plate and thereby x each disc with respect to one another. y

5. In a control device for controllable apparatus, a rotary shaft, a control unit on said shaft comprising a pair of metal discs, each disc having a body portion, a laterally extending flange over substantially 180 of the periphery thereof, with said disc having an aperture in the center thereof fitting over said shaft and an embossed annular rim spaced away from said aperture and deiining a lcavity in the body portion of said disc, insulating means for separating said discs, and insulating means on said shaft fitting the cavity of each of said discs to insulate the control unit from the shaft.

6. In a control device for controllable apparatus, power means for actuating said device,

and means for controlling the actuating inter val for said power means, said control means including a rotary member comprising a pair of coaxial conducting discs each having inwardly extending projections, and means for insulating said discs from one another andat the same time retaining the same in relatively fixed relation with respect to one another, said means comprising an insulatin plate having apertures positioned to correspond to the projections on each ing the shaft, and clutch means for connecting said power means with said shaft, including an electro-magnet having a pair of-energizing windings with each extending in a direction such that the polarity of the field and for onewinding neutralizes the field of the other winding, a control unit on said shaft including a pair of separated conducting segments, a contact for engagement with one of said segments to extend an energizing circuit through one of said magnet windings to actuate the clutch to .connectthe shaft and ,power means to rotate said shaft to a point at which said contact simultaneously engages both of said segments to extend a circuit through each of the windings of said magnet and cause the collapse of the energizing field for said magnetto deenergize the same and cause disengagement ofthe clutch means. y

8. An electric control device for controllable apparatus including a rotary shaft, a control unit on said shaft comprising a pair of conducting members, -an insulating disc intermediate said pair of lconducting members, with each of said conducting membersbeing fixedly supported on said insulating disc but out of Contact with one another, andinsulating means independent of said insulating disc on the outside of each of said conducting members for supporting said unit on said shaft and maintaining said unit out of electrical engagement therewith.

9. A control device for controllable apparatus,

` tance from one another, with the contact members in one group adapted to engage alternate .between the two groups of contact members for power means for actuating said device, and means for controlling the actuating interval of said power means, including a pair of coaxial control units rotatably mounted and positioned adjacent one another, a movable contact lmember for each 5 control unit with the contact members being supported in oppositely but laterally displaced positions with respect to one another on the device, with a control circuit being completed through one control unit or the other depending l upon the contact member selected by engagement of the selected contact member and the control vunit and a single stationary brush in continuous engagement with both of said control units. l

10. A control device` for a radio receiver including a plurality of rotatable control units supported in an assembly in axial alignment with respect to one another, means for completing control circuits through said control units, including two groups of movable contact members, with said groups being spaced apart and mounted on said control device so that the contact portions thereof are approximately 180 in an angular discontrol units and the contact members in the other group adapted to engage the remaining control units, electromagnet means on said device selectively attracting a contact member into engagement with a control unit, and a plurality of stationary brushes with one brush for each two adjacent control units.

11. In an electric tuning device for a radio receiver having rotary control means, a compact Y electro-magnet having at least two separated pole/ faces, means for driving said rotary control means, and a circuit for energizing said driving means, the combination of a movable contact in 4@ said circuitl to be attracted to the electro-magnet and moved into engagement with said rotary control means, said contact having an armature thereon for direct engagement with said pole faces, and means for adjustably mounting said armature on said contact for positioning the same so as to provide a substantially full faced contact between said armature and said pole faces so that said compact electro-magnet will exert a relatively large amount of pull on said armature 'with a relatively small amount of current in said electro-magnet, said mounting means including a pair of spaced apart apertured portions on said contact, an adjusting screw supported in each aperture with saidadjusting screws threadably 55 secured in corresponding apertures in said ar- Vmature to selectively move the ends of said armatures toward or away from said contact to provide an alignment with said electromagnet such as to obtain substantially full face contact 6c with said pole faces.

12. A 'radio receiver tuning system, including rotary tuning means, power means for driving the rotary tuning means and clutch means for connecting said power means with said rotary tuning means, said clutch means including an electromagnet having a pair of energizing windings with each winding extending in a direction such that the polarity of the eld for one winding neutralizes the field of the other winding, control means in said rotary tuning means including a 'pair of separated conducting portions xed with reference to one another and moving with said rotary tuning means, a contact for engagement with one of said conducting portions to extend an energizing circuit through one of said electromagnet windings to actuate the clutch means to connect the power means and rotary tuning means to rotate the latter to an angular position at which said contact simultaneously engages both of said conducting portions. to extend a circuit through each oi' the windings of said electromagnet and cause the collapse of the operating eld for said electromagnet to deenergize said operating field and cause disengagement of the clutch means from the rotary tuning means.

ALEXANDER W. PLENSLER. 

